Information
The Banner parameter specifies a file whose contents must be sent to the remote user before authentication is permitted. By default, no banner is displayed.
Rationale:
Banners are used to warn connecting users of the particular site's policy regarding connection. Presenting a warning message prior to the normal user login may assist the prosecution of trespassers on the computer system.
Solution
Edit or create a file ending in *.conf in the /etc/ssh/sshd_config.d/ directory or the /etc/ssh/sshd_config file and set the Banner parameter as follows:
Banner /etc/issue.net